1. Field of the Invention
The present invention relates to a coin sorting apparatus comprising a stationary member and a rotary disk disposed under the stationary member contiguously with a lower surface thereof. The coin sorting apparatus is constructed such that coins sliding along the lower surface of the stationary member are sorted according to diameters thereof as the rotary disk rotates.
2. Description of the Related Art
FIG. 13 shows a coin sorting apparatus disclosed in the applicant's Japanese patent application No. 2001-79206 filed on Mar. 19, 2001. In FIG. 13, the coin sorting apparatus comprises a stationary disk (stationary member) 101 and a rotary disk 2 disposed under the stationary disk 101 contiguously with a lower surface thereof. The rotary disk 2 comprises a disk body 22 supported for rotation about a shaft 20, and a resilient member 24 attached to an upper surface of the disk body 22.
An inlet opening 1a is formed in a central part of the stationary disk 101. The coin sorting apparatus is formed such that a coin fed through the inlet opening 1a of the stationary disk 101 slides along lower surface 1b (FIG. 14) of the stationary disk 101 as the rotary disk 2 rotates. A guide structure is formed in the stationary disk 101 for selectively guiding coins sliding along the lower surface 1b of the stationary disk 101, according to diameters of the coins.
As shown in FIG. 14, the guide structure comprises a coin passage 110 formed concavely in the lower surface 1b of the stationary disk 101. The coin passage 110 extends counterclockwise as viewed in FIG. 14 in a meandering spiral from the inlet opening 1a toward a periphery of the stationary disk 101. The coin passage 110 has, arranged from the inlet opening 1a toward the periphery of the stationary disk 101, a large-coin passage section 110a, a medium-coin passage section 110b and a small-coin passage section 110c. The large-coin passage section 110a has a width that permits passage of large, medium and small coins. The medium-coin passage section 110b has a width L1 that permits passage of only medium and small coins. The small-coin passage section 110c has a width L2 that permits passage of only small coins.
The large-coin passage section 110a has a coin entrance 11 facing the inlet opening 1a, and stairs 112a and 112b formed at an interval on a downstream side with respect to the coin entrance 11. The stairs 112a and 112b are formed to reduce a thickness of a gap between the resilient member 24 of the rotary disk 2 (FIG. 13) and the large-coin passage section 110a stepwise toward a downstream side thereof. By virtue of the stairs 112a and 112b, overlapping coins are separated from each other to ensure that coins do not overlap each other and move in a single file in the coin passage 110.
A coin returning part 113 is formed contiguously with the inlet opening 1a on a downstream side with respect to the stairs 112a and 112b. There is a possibility that a pair of overlapping coins pass the stairs 112a and 112b without being separated from each other. These overlapping coins include an “upper coin” that is contiguous with the stationary disk 101 and a “lower coin” that is contiguous with the rotary disk 2. Thus, the coin returning part 113 is configured to return the “lower coin” toward the inlet opening 1a. 
Since the large-coin passage section 110a extends spirally away from the center toward a circumference of the stationary disk 101, it is intended that outer edges of all the coins moving therein should engage a radial inner edge portion 110i-a thereof.
A large-coin sorting guide 115a is disposed radially outside the medium-coin passage section 110b to guide only large coins selectively and to eject the large coins in a substantially tangential direction. The large-coin sorting guide 115a has a step 116a and an ejecting passage 117a. The step 116a is formed at a boundary between the large-coin passage section 110a and the medium-coin passage section 110b. The step 116a is formed such that only a peripheral part of each of the large coins of diameters greater than the width L1 of the medium-coin passage section 110b runs onto the step 116a. 
The ejecting passage 117a has a guide edge 118a for guiding a coin that has run onto the step 116a for movement in a substantially tangential direction, and an outlet 119a through which the coin guided by the guide edge 118a is ejected to an exterior. Since all the coins engage the radial inner edge portion 110i-a, medium coins and small coins respectively having diameters smaller than the width L1 do not run onto the step 116a and move into the medium-coin passage section 110b. 
A medium-coin sorting guide 115b is disposed radially outside the small-coin passage section 110c to guide only medium coins selectively, and to eject the medium coins in a substantially tangential direction. The medium-coin sorting guide 115b, similarly to the large-coin sorting guide 115a, has a step 116b and an ejecting passage 117b. 
The step 116b is formed at a boundary between the medium-coin passage section 110b and the small-coin passage section 110c. The step 116b is formed such that only a peripheral part of each of the medium coins of diameters greater than the width L2 of the small-coin passage section 110c runs onto the step 116b. The step 116b is formed by an adjustable step plate S2′. The ejecting passage 117b, similarly to the ejecting passage 117a of the large-coin sorting guide 115a, has a guide edge 118b and an outlet 119b. 
Since a downstream part of the medium-coin passage section 110b extends away from the center toward the outer circumference of the stationary disk 101, it is intended that outer edges of all the coins moving therein should engage a radial inner edge portion 110i-b thereof. Thus, small coins of a diameter smaller than the width L2 move into the small-coin passage section 110c without running onto the step 116b. 
The small-coin passage section 110c extends downstream toward an inner circumference and then toward the outer circumference of the stationary disk 101, and terminates in a small-coin sorting guide 115c having an outlet 119c. 
Foreign matter sorting structure 108 is arranged on the stationary disk 101. The foreign matter sorting structure 108 has a foreign matter passage 180 branched off from the small-coin passage section 110c, and a stepped gate 182 formed at a junction of the small-coin passage section 110c and the foreign matter passage 180. The foreign matter sorting structure 108 selectively ejects foreign matter, such as paper clips, thinner than a thinnest coin.
This coin sorting apparatus has the following problems. The radial inner edge portion 110i-a (110i-b), which is configured to engage the outer edges of all the coins, defines a shoulder formed of a height less than a thickness of a thinnest coin so as not to prevent the “lower coin” from returning, e.g. through the coin returning part 113, toward the inlet opening 1a. On the other hand, as shown in FIG. 15, there is a possibility that coins to be sorted include a deformed coin C′, bent such that a convex side thereof faces the lower surface 1b of the stationary disk 101. If the deformed coin C′ is fed into the coin passage 110 with its bending axis in a substantially tangential direction with respect to the coin passage 110, there is a possibility that an outer edge of the deformed coin C′ does not engage the radial inner edge portion 110i-a (110i-b). In this case, the coin sorting apparatus is likely to fail in performing an intended coin sorting operation and cause a miss-sorting and/or a hold-up of coins therein.
In addition, considering a case of a coin jam between the stationary disk 101 and the rotary disk 2, it is advantageous if a sorting process can be continued by rotating the rotary disk 2 in reverse temporarily, and then continuing to rotate the rotary disk 2 forwardly in normal operation. However, in the above coin sorting apparatus, the guide edges 118a and 118b of the ejecting passages 117a and 117b include stepped portions 118a′ and 118b′. The stepped portions 118a′ and 118b′ define vertical walls formed transversely of coin-passing directions between the steps 116a and 116b and the ejecting passages 117a and 117b, respectively.
Therefore, once coins have passed into the ejecting passage 117a and 117b through the stepped portions 118a′ and 118b′, these coins cannot return to an upstream side with respect to the stepped portions 118a′ and 118b even if the rotary disk is reversely rotated. In this case, when the rotary disk 2 is rotated forwardly again, the coin sorting apparatus is likely to cause the miss-sorting and/or the hold-up of the coins therein, and fail to resume a normal coin sorting operation.